How to Install Seafile on Ubuntu 15.04 (Vivid Vervet)

Seafile is a private cloud software, it supports encrypted file libraries to store data securely. To encrypt files in a library, you need to set a password when you create the library. The password won't be stored on Seafile cloud, so even the adminastrator of the servers cannot view your encrypted data without the password. This tutorial shows the installation of Seafile on Ubuntu 15.04.